The purpose for this research is to identify biological and psychological markers that are associated with risk for alcoholism and drug abuse. We are particularly interested in differences in the response to alcohol and methylphenidate of individuals with and without a family history of alcoholism. Subjects are exposed to one familiarization session in which they drink water, three identical sessions in which they drink 0.75 g/kg ethanol, and one session with placebo. Two subsequent sessions involve methylphenidate (30 mg, p.o.) and placebo in counterbalanced order. The dependent measures for all sessions include autonomic, facial electromyograph, general motor activity, hormonal, and subjective responses. The subjects are 21 to 25 year old males with and without a family history of alcoholism. Preliminary results indicate that family history positive subjects show larger responses to alcohol than family history negative subjects. Moreover, the pattern of responding in heart rate, positive mood, general motor activity, and hormonal responses suggests that the family history positive subjects receive more reward from alcohol. The significance of these results is that it suggests psychobiological mechanism whereby familial risk for alcoholism may be expressed in terms of ultimate manifestation of the disorder. Future plans for this study involve: 1) increasing the cell sizes to allow more definitive conclusions, 2) analyzing the data in terms of other risk factors, including the DRD2 polymorphism, subject's history of conduct disorder and hyperactivity, and subject's antisocial characteristics in adulthood, and 3) investigating time of day effects in the response to alcohol.